Intestinal Absorption of Triterpenoids and Flavonoids from Glycyrrhizae radix et rhizoma in the Human Caco-2 Monolayer Cell Model.

has been used as a traditional Chinese medicine for the treatment of various diseases. Triterpenoids and flavonoids from the plant have many beneficial effects and their chemical structures are modified in the gastrointestinal tract after oral administration. However, absorption of these triterpenoids and flavonoids still needs to be defined. Here, the uptake and transepithelial transport of the selected major triterpenoids, glycyrrhizin (), glycyrrhetic acid-3--mono-β-d-glucuronide (), and glycyrrhetinic acid (); and the selected major flavonoids, licochalcone A (), licochalcone B (), licochalcone C (), echinatin (), isoliquiritin apioside (), liquiritigenin (), liquiritin apioside () isolated from , were investigated in the human intestinal epithelium-like Caco-2 cell monolayer model. Compounds , -, and were designated as well-absorbed compounds, and were designated as moderately absorbed ones, and , , and were assigned for the poorly absorbed ones. The absorption mechanism of well and moderately absorbed compound was mainly passive diffusion to pass through the human intestinal Caco-2 cell monolayer. These findings provided useful information for predicting their oral bioavailability and the clinical application.